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honokaBiuhonokaBiu
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Merge pull request onlyliuxin#32 from conf1102/master
Homework 3rd
2 parents 3139bf5 + 2389735 commit 185baa7

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‎group20/404130810/src/com/coderising/download/DownloadThread.java

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package com.coderising.download;
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import java.io.File;
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import java.io.IOException;
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import java.io.RandomAccessFile;
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import java.util.concurrent.CountDownLatch;
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import com.coderising.download.api.Connection;
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public class DownloadThread extends Thread{
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Connection conn;
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int startPos;
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int endPos;
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CountDownLatch latch;
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File file = new File("C://download.mp3");
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public DownloadThread( Connection conn, int startPos, int endPos, CountDownLatch latch){
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this.conn = conn;
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this.startPos = startPos;
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this.endPos = endPos;
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this.latch = latch;
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}
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public void run(){
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RandomAccessFile raf = null;
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try {
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byte[] byteRead = conn.read(startPos, endPos);
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raf = new RandomAccessFile(file, "rw");;
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raf.seek(startPos);
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raf.write(byteRead);
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} catch (IOException e) {
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e.printStackTrace();
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}finally{
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latch.countDown();
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try {
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raf.close();
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} catch (IOException e) {
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e.printStackTrace();
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}
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conn.close();
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}
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}
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}

‎group20/404130810/src/com/coderising/download/FileDownloader.java

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package com.coderising.download;
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import java.io.IOException;
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import java.util.concurrent.CountDownLatch;
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import java.util.concurrent.CyclicBarrier;
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import com.coderising.download.api.Connection;
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import com.coderising.download.api.ConnectionException;
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import com.coderising.download.api.ConnectionManager;
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import com.coderising.download.api.DownloadListener;
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import com.coderising.download.impl.ConnectionManagerImpl;
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import com.coderising.download.utils.FileDownloadUtil;
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public class FileDownloader {
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String url = "http://localhost:8080/MyServer/test.exe";
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DownloadListener listener;
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ConnectionManager cm;
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public FileDownloader(String _url) {
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this.url = _url;
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cm = new ConnectionManagerImpl();
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}
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public void execute() throws IOException {
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// 在这里实现你的代码， 注意： 需要用多线程实现下载
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// 这个类依赖于其他几个接口, 你需要写这几个接口的实现代码
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// (1) ConnectionManager , 可以打开一个连接，通过Connection可以读取其中的一段（用startPos,
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// endPos来指定）
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// (2) DownloadListener, 由于是多线程下载， 调用这个类的客户端不知道什么时候结束，所以你需要实现当所有
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// 线程都执行完以后， 调用listener的notifiedFinished方法， 这样客户端就能收到通知。
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// 具体的实现思路：
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// 1. 需要调用ConnectionManager的open方法打开连接，
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// 然后通过Connection.getContentLength方法获得文件的长度
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// 2. 至少启动3个线程下载， 注意每个线程需要先调用ConnectionManager的open方法
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// 然后调用read方法， read方法中有读取文件的开始位置和结束位置的参数， 返回值是byte[]数组
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// 3. 把byte数组写入到文件中
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// 4. 所有的线程都下载完成以后， 需要调用listener的notifiedFinished方法
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// 下面的代码是示例代码， 也就是说只有一个线程， 你需要改造成多线程的。
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Connection conn = null;
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try {
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conn = cm.open(url);
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int length = conn.getContentLength();
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int[] posArr = FileDownloadUtil.generateDownloadPosArr(length);
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CountDownLatch latch = new CountDownLatch(3);
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for (int i = 0; i < posArr.length; i++) {
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if (i == posArr.length - 1) {
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new DownloadThread(cm.open(url), posArr[i], length, latch).start();
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} else {
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new DownloadThread(cm.open(url), posArr[i], posArr[i + 1] - 1, latch).start();
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}
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}
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latch.await();
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System.out.println("Download Finished");
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} catch (ConnectionException e) {
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e.printStackTrace();
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} catch (InterruptedException e) {
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e.printStackTrace();
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} finally {
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if (conn != null) {
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conn.close();
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}
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}
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}
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public void setListener(DownloadListener listener) {
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this.listener = listener;
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}
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public void setConnectionManager(ConnectionManager ucm) {
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this.cm = ucm;
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}
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public DownloadListener getListener() {
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return this.listener;
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}
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public static void main(String[] args) throws IOException {
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new FileDownloader("http://localhost:8080/MyServer/Test.mp3").execute();
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}
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}

‎group20/404130810/src/com/coderising/download/FileDownloaderTest.java

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package com.coderising.download;
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import java.io.IOException;
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import org.junit.After;
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import org.junit.Before;
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import org.junit.Test;
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import com.coderising.download.api.ConnectionManager;
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import com.coderising.download.api.DownloadListener;
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import com.coderising.download.impl.ConnectionManagerImpl;
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public class FileDownloaderTest {
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boolean downloadFinished = false;
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@Before
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public void setUp() throws Exception {
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}
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@After
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public void tearDown() throws Exception {
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}
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@Test
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public void testDownload() throws IOException {
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String url = "http://localhost:8080/MyServer/Test.mp3";
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FileDownloader downloader = new FileDownloader(url);
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ConnectionManager cm = new ConnectionManagerImpl();
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downloader.setConnectionManager(cm);
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downloader.setListener(new DownloadListener() {
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@Override
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public void notifyFinished() {
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downloadFinished = true;
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}
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});
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downloader.execute();
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// 等待多线程下载程序执行完毕
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while (!downloadFinished) {
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try {
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System.out.println("还没有下载完成，休眠五秒");
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//休眠5秒
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Thread.sleep(5000);
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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}
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System.out.println("下载完成！");
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}
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}

‎group20/404130810/src/com/coderising/download/api/Connection.java

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package com.coderising.download.api;
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import java.io.IOException;
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public interface Connection {
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/**
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* 给定开始和结束位置， 读取数据， 返回值是字节数组
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* @param startPos 开始位置， 从0开始
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* @param endPos 结束位置
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* @return
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*/
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public byte[] read(int startPos,int endPos) throws IOException;
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/**
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* 得到数据内容的长度
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* @return
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*/
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public int getContentLength();
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/**
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* 关闭连接
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*/
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public void close();
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}

‎group20/404130810/src/com/coderising/download/api/ConnectionException.java

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package com.coderising.download.api;
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public class ConnectionException extends Exception {
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}

‎group20/404130810/src/com/coderising/download/api/ConnectionManager.java

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package com.coderising.download.api;
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public interface ConnectionManager {
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public Connection open(String url) throws ConnectionException;
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}

‎group20/404130810/src/com/coderising/download/api/DownloadListener.java

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package com.coderising.download.api;
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public interface DownloadListener {
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public void notifyFinished();
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}

‎group20/404130810/src/com/coderising/download/impl/ConnectionImpl.java

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package com.coderising.download.impl;
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import java.io.ByteArrayOutputStream;
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import java.io.File;
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import java.io.IOException;
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import java.io.InputStream;
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import java.io.RandomAccessFile;
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import java.net.HttpURLConnection;
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import java.net.URL;
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import com.coderising.download.api.Connection;
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public class ConnectionImpl implements Connection {
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private HttpURLConnection httpConn;
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public ConnectionImpl(String urlStr) {
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URL url;
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try {
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url = new URL(urlStr);
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httpConn = (HttpURLConnection) url.openConnection();
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} catch (IOException e) {
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e.printStackTrace();
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}
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}
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@Override
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public byte[] read(int startPos, int endPos) throws IOException {
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System.out.println("Start Reading");
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System.out.println("StartPos: " + startPos);
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System.out.println("EndPos: " + endPos);
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ByteArrayOutputStream baos = new ByteArrayOutputStream();
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InputStream is = httpConn.getInputStream();
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is.skip(startPos);
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int downloadLengh = endPos - startPos;
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byte[] b = new byte[1024];
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int total = 0;
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int len = -1;
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while ((len = is.read(b)) != -1) {
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baos.write(b, 0, len);
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total = total + len;
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if (total == downloadLengh) {
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break;
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}
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}
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is.close();
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baos.close();
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System.out.println("End Reading");
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return baos.toByteArray();
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}
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@Override
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public int getContentLength() {
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return httpConn.getContentLength();
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}
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@Override
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public void close() {
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httpConn.disconnect();
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}
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}

‎group20/404130810/src/com/coderising/download/impl/ConnectionManagerImpl.java

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package com.coderising.download.impl;
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import com.coderising.download.api.Connection;
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import com.coderising.download.api.ConnectionException;
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import com.coderising.download.api.ConnectionManager;
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public class ConnectionManagerImpl implements ConnectionManager {
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@Override
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public Connection open(String urlStr) throws ConnectionException {
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Connection conn = new ConnectionImpl(urlStr);
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return conn;
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}
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}

‎group20/404130810/src/com/coderising/download/utils/FileDownloadUtil.java

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package com.coderising.download.utils;
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public class FileDownloadUtil {
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public static int[] generateDownloadPosArr(int length){
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int[] posArr = new int[3];
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int firstPos = length/3;
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int secondPos = length/3 * 2;
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posArr[0] = 0;
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posArr[1] = firstPos;
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posArr[2] = secondPos;
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return posArr;
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}
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public static void main(String[] args) {
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FileDownloadUtil.generateDownloadPosArr(1000);
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}
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}

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